The present invention is directed to a coaster for a bottle, can, or mug of beverage, such as beer or ale. The conventional coaster is placed under a beer bottle, or the like, in order to prevent the slipping or sliding the bottle on the supporting surface, and to catch and retain liquid condensation or any minor spillage that may occur. There is known to provide a coaster that is continuously lit up, in order to provide an aesthetic effect.
The present invention is directed to a coaster that is lit up only when the bottle of beer, or the like, supported thereon is empty or near-empty, in order to inform the bartender, or the like, of the need to approach the customer or person to see if he or she wishes another, full bottle.